Apparatus and associated methods relate to providing robust synchronization of a Radio-Frequency (RF) communication in a severe-fading environment. A first portion of a detected RF signal is auto-correlated with a second portion of the detected RF signal. The first and second portions are time-separated by the predetermined time delay separating the first and second code-sequences. A third portion of the detected RF signal is sync-correlated with a sync-sequence so as to generate a sync-correlation signal. The third portion is of the predetermined length of the sync sequence and includes the first and second portions of the detected RF signal used to generate the auto-correlation signal. The auto-correlation signal is multiplied by the sync-correlation signal so as to generate a combined synchronization signal. A peak in the combined synchronization signal is then detected. This peak can be indicative of a synchronization time of an authorized communication.